$\dfrac{2}{4} - \dfrac{2}{6} = {?}$
Answer: $ = {\dfrac{2 \times 3}{4 \times 3}} - {\dfrac{2 \times 2}{6 \times 2}} $ $ = {\dfrac{6}{12}} - {\dfrac{4}{12}} $ $ = \dfrac{{6} - {4}}{12} $ $ = \dfrac{2}{12}$